Icon/KB 1.353 superseded or more options?

[eugenebuilt]

TL;DR: table just below maps new UEM 1.363" compression height part #s to legacy 1.353" part #s.

Line/Old Part#/Old Dish/New UEM Part#/New Dish
Icon Premium Forged/IC668/27.5cc/IC10180/27cc
Icon Premium Forged/IC944/21cc/IC10181/22cc
Icon Premium Forged/IC945/10.8cc/IC10182/10.8cc
Icon FHR/IC???/27cc/IC10180/27cc
KB Hyper/KB???/21cc/KB10177/21cc
KB Hyper/KB424/27.5cc/KB10179/27.5cc

More context below if your parts are stuck at the machine shop like mine and you're digging for stuff to do like me.

What's the difference between the old and new parts? A couple differences on the new parts: 1. pin height is 1.363 on the new part instead of 1.353 on the long time staple and 2. metric piston rings instead of SAE. These changes mean obviously a different set of pistons rings at 1.5, 1.5, 4.0MM are needed for the new part instead of the standard 5/64, 5/64, 3/16 rings used on the long time 1.353 series. Next obvious change is clearance to deck potentially saving $$ at the machine shop by reducing the need to machine the deck by .010". Some differences in dish sizes too according to spec on UEM site.

I'm making this post for a recent potential development in the widely used Jeep stroker Icon and KB series. This development is new to me, let me know in the comments if this is a long known development and I'm just late to the party.

It's unclear to me if the development is that UEM:
1. expanded options in pin height by adding a 1.363 in addition to the long time 1.353 stroker staple, or
2. if UEM discontinued and superseded the long time 1.353 stroker staple with the new parts having 1.363" pin height

My story further below suggests #2 is likely. Does anyone know for sure which it is? Feel free to jump in. Jump in also if I'm entirely out of touch with reality on this.

What prompted this post? Well I'm building a stroker and tried to order IC944 at 030 over and immediately ran into a hurdle finding this part at any dealer outside of a kit. I just want the pistons not the kit. At the time of my order and still at the time of this post all dealer sites indicate the IC944.030 is out of stock and expected to ship in several weeks if ordered today. Other bore sizes with other dish sizes are also out of stock or appear available in limited quantity.

So I called a couple dealers to learn if they know more about availability of 030 over and learned that the dealers aren't able to place an order for IC944.030 even though the websites will still allow you to add to cart for purchase. One dealer suggested that when parts are listed at a sale price, as the 030 was at the time, it often suggests that the part is on the chopping block at the manufacturer.

Then I called UEM directly where I learned by phone that UEM also cannot place an order for the part or cite availability of the IC944 because it has been superseded by a new part number, implying also that the entire line of Icon and KB series 1.353 pin height may be destined to be superseded by new parts. This is from the mouth of UEM, not me speculating, not internet or AI slop, straight from the horses mouth.

The reason I'm unsure if the old staples are superseded or if UEM instead expanded their options is because the new part numbers such as IC10181 specifically cite " +.010" Compression Height" in the description on UEM's site so I'm keeping an open mind that the person at UEM may have been mistaken about the 1.353 series being superseded and maybe the new part represents expanded options to buy stroker pistons at a new 1.363 pin height in addition to the 1.353, and that the 1.353 is just running low. Again, jump in if you have authoritative knowledge on this.

The reason I'm mapping new part numbers to old part numbers here is because as of this post dealers haven't yet connected the dots and new part numbers don't appear on dealer catalogues online and dealers don't see new parts in their catalogue if you call them. This will likely change at some point in the future when the dealers connect the dots. One exception to this is that IC10181.030, which is the replacement for IC944.030, now appears on the Summit site due to my correspondence with Summit. Pistons with new part numbers can be ordered directly from UEM often at a greater price than from the dealer. For example UEM quoted $695 for IC10181.030 and the Summit site now shows the same part for $595.

Hopefully this helps someone somewhere until dealers get their poop in a group and make the new parts available online for easy ordering. This may impact your build plans if you're currently or in the near future seeking a set of the 1.353 pin height series such as IC944.030 which is sold out or other bore sizes should they become sold out soon. Your build may not be impacted if you're going with a piston from a different manufacturer or if you're buying a kit (unless this piston is in your kit).

If you hung with my post to this point call your machine shop and tell them you need your stuff back so you can get to work. Thanks folks for the many years of pioneering knowledge and wisdom and dad jokes archived here and other forums.

UEM site: https://uempistons.com/catalogue?Make=AMC&efamily=AMC

[eugenebuilt]

KB Hyper/KB???/21cc/KB10177/21cc

Filling the blank above :

KB Hyper/ KB438C /21cc/KB10177/21cc

Shout out to 6spdYJ for helping fill in the blank in the post here: viewtopic.php?t=6896

[Gorilla]

I had been waiting quite a while on standard bore -21cc KB pistons for my stroker kit. Turns out the wait was worth it. Ended up with the updated ones which sit 0.014 in the hole vs the old ones being .024 as informed by the people at Clegg.

They are the KB10177-STD

Combined with a 0.027" Commetic head gasket improves the quench without machining to 0.041".